2. Field of the Invention
The invention pertains to systems for disinfecting condensation and moisture producing apparatus within air handling systems by the periodic exposure of the apparatus to an anti-microbial gas.
Apparatus producing condensation moisture within air handling systems is subject to contamination by the growth of microorganisms existing on the moist surfaces of the apparatus. Such situations occur in air conditioners, dehumidifiers and other air cooling systems wherein air passing through heat exchanging coils is rapidly cooled and the moisture within the air condenses on the coils and falls into a drip pan or other apparatus for removing moisture.
Microbial growth is common on surfaces where moisture, minerals and organic substances are present, and the growth of such microorganisms on condensing apparatus surfaces reduces the heat exchange efficiency and the overall performance of the apparatus. Additionally, microbial growth produces microorganisms which can become airborne during the operation of the air handling system, therein contaminating ducts and occupied spaces. Such contamination of indoor air has been widely documented, and is a major cause of illness among individuals within office buildings and the like having sealed windows wherein air circulation is only through central cooling and heating units. Contaminated air conditioning systems are known to cause "sick building syndrome", Legionnaire's disease, and hypersensitivity pneumonitis.
The problem of contamination of air handling systems such as those used in commercial buildings, private dwellings and vehicles is particularly acute in warm climate areas that require lengthy air conditioner operation without the opportunity to permit the moisture producing coils, drip pans, and the like to dry. In an effort to control contamination of air handling systems by microbial growth on condensation apparatus, various techniques have been employed. For instance, condensation collecting drip pans are designed to remove the majority of moisture as quickly as possible from the air handling system, but residual moisture will remain. Further, it is recommended that the condensation producing apparatus of air cooling equipment be regularly manually cleaned and disinfected. However, such regular and routine maintenance is often overlooked, and the use of conventional disinfecting techniques creates problems because of the dissipation of disinfectants into the air flowing through the system. Accordingly, air cooling systems are not usually regularly maintained and cleaned to avoid the microbial contamination which occurs and many occupants of buildings and vehicles having contaminated air systems are subject to allergies and illnesses difficult to trace and diagnose.
2.
Description of Related Art
The aforementioned problems with respect to microbial growth within air handling systems has long been recognized, but has not been effectively solved. It is known that the treatment of air within air handling systems by ultraviolet light frequencies can be helpful in controlling microbial growth, and apparatus for doing so is shown in U.S. Pat. Nos. 2,628,083 and 3,100,679. Likewise, an ultraviolet device is shown in U.S. Pat. No. 4,990,313 which would be suitable for use with domestic air cooling systems.
Ozone is known as a strong oxidant and an effective sterilant, and has been used to purify or sterilize refrigerated air, as shown in U.S. Pat. Nos. 2,248,713 and 3,421,836.
While the aforementioned patents propose to deal with the problem of the microbial contamination of air cooling systems, ultraviolet light devices have not proven effective to sufficiently sterilize the air and surfaces within air handling systems to control microbial growth, and while those systems using ozone more readily disinfect inaccessible surfaces than can be achieved with the ultraviolet systems, the exposure of humans to ozone is considered detrimental.